System for combining wireless sensor networks and method thereof

ABSTRACT

A system for combining wireless sensor networks includes a first sink transmitting a request to combine (RTC) and first routing-information. First nodes propagate data and instructions in a first wireless sensor network. The first nodes broadcast the RTC when the first nodes are boundary nodes. The first routing-information are established based on first transmission paths between the first sink and the first nodes. A second sink receives the RTC and the first routing-information from the first sink. The second sink transmits second routing-information to the first sink. The second routing-information are established based on second transmission paths between the second sink and the second nodes. The second node relays the RTC to the second sink according to a flag in a packet of the RTC. The first wireless sensor network combines with the second wireless sensor network to exchange the first routing-information and the second routing-information.

FIELD

The disclosure relates to a system and method for combining andestablishing a secure channel for a distributed wireless sensor network,especially a distributed system capable of dynamically exchangingrouting-information to extend the transmission range of a wirelesssensor network.

BACKGROUND

A wireless sensor network (WSN) is a network system to which one or moresink and sensor nodes contribute. The sink and the sensor nodescommunicate wirelessly. The WSN transmits sensor data at low power usingmultiple hops and dynamic transmission paths, and supports a variety ofnetwork topologies.

The transmission range of the WSN is limited by the distribution of thesensor nodes. A single WSN is not flexible in its transmission range.The user needs to set more sensor nodes when they want to extend thetransmission range. Different WSNs in the same environment cannot atpresent communicate with each other

SUMMARY

In the disclosure, a first sink and a second sink exchange firstrouting-information of a first WSN and second routing-information of asecond WSN according to a request to combine (RTC). The first WSN andthe second WSN communicate with each other by exchanging the firstrouting-information and the second routing-information. The limitationof the transmission range in single WSN can be resolved by combiningdifferent WSNs.

The disclosure provides a system for combining WSNs, applied to a firstWSN and a second WSN. The first WSN comprises the first sink and firstnodes. The first sink transmits RTC and the first routing-information.The first nodes relay data and instructions in the first WSN. The firstnodes broadcast the RTC when the first nodes are boundary nodes. Thefirst routing-information are established based on the firsttransmission paths between the first sink and the first nodes. Thesecond WSN comprises the second sink and second nodes. The second sinkreceives RTC and the first routing-information from the first sinkaccording to the RTC. The second nodes relay the data and instructionsin the second WSN. The second routing-information are established basedon the second transmission paths between the second sink and the secondnodes. The second nodes receive RTC and determine whether or not torelay the RTC to the second sink, according to a flag of the RTC. Thefirst sink and the second sink communicate with each other according tothe first routing-information and the second routing-information.

The disclosure provides a method of combining WSNs. Firstrouting-information are obtained by first transmission paths between afirst sink and first nodes. Second routing-information are obtained bysecond transmission paths between a second sink and second nodes. An RTCis transmitted by the first sink. Data and instructions are relayed inthe first WSN by the first sink. The RTC is broadcast by boundary nodesin the first WSN. The RTC is received by the second nodes. A flag in theRTC determines whether or not it should be relayed to the second sink bythe second nodes. The second routing-information are transmitted to thefirst sink when the RTC is received by the second sink. The firstrouting-information are transmitted to the second sink by the firstsink. The first sink and the second sink communicate with each otheraccording to the first routing-information and the secondrouting-information.

BRIEF DESCRIPTION OF THE DRAWINGS

Implementations of the present disclosure will now be described, by wayof example only, with reference to the attached figures, wherein:

FIG. 1 illustrates a block diagram of a system for combining wirelesssensor networks according to an exemplary embodiment of the presentdisclosure.

FIG. 2 illustrates the system of FIG. 1 according to an exemplaryembodiment of the present disclosure.

FIG. 3 illustrates communication between sinks by internet in the systemof FIG. 1 according to the exemplary embodiment of the presentdisclosure.

FIG. 4 illustrates the system of FIG. 1 according to another exemplaryembodiment of the present disclosure.

FIG. 5 illustrates a flowchart of a method for the system of FIG. 1according to exemplary embodiment of the present disclosure.

FIG. 6 is a flow chart illustrating a request to combine (RTC) which istransmitted by sink according to exemplary embodiment of the presentdisclosure.

FIG. 7 is a flow chart illustrating a response to a RTC transmitted bysink according to exemplary embodiment of the present disclosure.

FIG. 8 is a flow chart illustrating a RTC which is received by nodesaccording to exemplary embodiment of the present disclosure.

FIG. 9 is a flow chart illustrating a response to a RTC received bynodes according to exemplary embodiment of the present disclosure.

DETAILED DESCRIPTION

It will be appreciated that for simplicity and clarity of illustration,where appropriate, reference numerals have been repeated among thedifferent figures to indicate corresponding or analogous elements. Inaddition, numerous specific details are set forth in order to provide athorough understanding of the embodiments described herein. However, itwill be understood by those of ordinary skill in the art that theembodiments described herein can be practiced without these specificdetails. In other instances, methods, procedures, and components havenot been described in detail so as not to obscure the related relevantfeature being described. Also, the description is not to be consideredas limiting the scope of the embodiments described herein. The drawingsare not necessarily to scale and the proportions of certain parts havebeen exaggerated to better illustrate details and features of thepresent disclosure.

Several definitions that apply throughout this disclosure will now bepresented.

The term “coupled” is defined as connected, whether directly orindirectly through intervening components, and is not necessarilylimited to physical connections. The connection may be such that theobjects are permanently connected or releasably connected. The term“substantially” is defined to be essentially conforming to theparticular dimension, shape, or other feature that the term modifies,such that the component need not be exact. The term “comprising,” whenutilized, is “including, but not necessarily limited to”; itspecifically indicates open-ended inclusion or membership in theso-described combination, group, series, and the like. References to“an” or “one” exemplary embodiment in this disclosure are notnecessarily to the same exemplary embodiment, and such references mean“at least one”.

FIG. 1 illustrates a block diagram of a system for combining wirelesssensor networks (hereinafter “the system”) according to an exemplaryembodiment of the present disclosure. As shown in FIG. 1, the systemcomprises a first wireless sensor network 110 and a second wirelesssensor network 120. The first wireless sensor network 110 comprises afirst sink 111 and a plurality of first nodes 112. Firstrouting-information are established according to first transmissionpaths between the first sink 111 and the first nodes 112. A request tocombine (RTC) and the first routing-information are transmitted by thefirst sink 111. The first nodes 112 relay data and instructions in thefirst wireless sensor network 110, and the first nodes 112 broadcast theRTC when the first nodes 112 are boundary nodes. The second wirelesssensor network 120 comprises a second sink 121 and a plurality of secondnodes 122. Second routing-information are established according tosecond transmission paths between the second sink 121 and the secondnodes 122. The second sink 121 receives the RTC. The second sink 121receives the first routing-information from the first sink 111 accordingto the RTC. The second nodes 122 relay the data and instructions in thesecond wireless sensor network 120. The second nodes 122 receive the RTCand determine whether or not to relay the RTC to the second sinkaccording to a flag of the RTC. The flag indicates instructions andtypes of instructions. The types of the instructions compriseinstruction from the same wireless sensor network, instruction fromdifferent wireless sensor networks, and the instruction of the RTC.

FIG. 2 illustrates the system of FIG. 1 according to an exemplaryembodiment of the present disclosure. In FIG. 2, the system comprises afirst wireless sensor network 210, a first sink 211, a plurality offirst nodes 212, a second wireless sensor network 220, a second sink221, and a plurality of second nodes 222. The first wireless sensornetwork 210 comprises the first sink 211 and the first nodes 212. Thesecond wireless sensor network 220 comprises the second sink 221 and thesecond nodes 222. The first nodes 212 collect sensor data in the firstsensor network 210, and transmit the sensor data to the first sink 211.The second nodes 222 collect sensor data in the second sensor network220, and transmit the sensor data to the second sink 221. The first sink211 and the second sink 221 belong to different wireless sensornetworks. The first sink 211 transmits the RTC for discovering wirelesssensor network which can be combined. The first nodes 212 relay the RTCto a next node when the first nodes 212 are not the boundary nodes inthe first wireless sensor network 210. The first nodes 212 broadcast theRTC when the first nodes 212 are boundary nodes. The second nodes 222relay the RTC to the second sink 221 according to therouting-information of the second nodes 222. The second sink 221transmits response to RTC and the second routing-information to thefirst sink 211 according to the original transmitting path when thefirst sink 211 and the second sink 221 are not connected to internet.The first sink 211 transmits the first routing-information to the secondsink 221 according to the second routing-information after receiving theRTC and the second routing-information. The first wireless sensornetwork 210 and the second wireless sensor network 220 communicate witheach other by exchanging the first routing-information and the secondrouting-information. The first sink 211 communicates with the secondsink 221 according to the first routing-information and the secondrouting-information.

FIG. 3 illustrates communication between sinks by internet in the systemof FIG. 1 according to the exemplary embodiment of the presentdisclosure. As shown in FIG. 3, the system comprises a first wirelesssensor network 310, a first sink 311, a plurality of first nodes 312, asecond wireless network 320, a second sink 321, and a plurality ofsecond nodes 322. The first wireless sensor network 310 comprises thefirst sink 311 and the first nodes 312. The second wireless sensornetwork 320 comprises the second sink 321 and second nodes 322. Thefirst nodes 312 collect sensor data in the first wireless sensor network310 and transmit the sensor data to the first sink 311. The second nodes322 collect sensor data in the second wireless sensor network 320 andtransmit the sensor data to the second sink 321. The first sink 311 andthe second sink 321 belong to different wireless sensor networks. Thefirst sink 311 transmits a RTC for discovering other wireless sensornetworks. The first nodes 312 relay the RTC to next node when the firstnodes 312 are not the boundary node in the first wireless sensor network310. The first nodes 312 broadcast the RTC when the first nodes 312 areboundary nodes. The second nodes 322 relay the RTC to the second sink321 according to the routing-information of the second nodes 322. Thesecond sink 321 transmits a response to RTC and secondrouting-information to the first sink 311 according to the internet 330when the first sink 311 and the second sink 321 are connected to theinternet 330. After receiving the response to RTC and the secondrouting-information, the first sink 311 transmits a firstrouting-information to the second sink 321 according to the internet330. The first wireless sensor network 310 and the second wirelesssensor network 320 communicate with each other by exchanging the firstrouting-information and the second routing-information. The first sink311 communicates with the second sink 321 according to the firstrouting-information and the second routing-information.

FIG. 4 illustrates the system of FIG. 1 according to another exemplaryembodiment of the present disclosure. As shown in FIG. 4, the systemcomprises a first base station 410, a first wireless sensor network 411,a second base station 420, a second wireless sensor network 421, a thirdbase station 430, and a third wireless sensor network 431. The firstbase station 410 collects sensor data of the first sensor network 411from a first sink 412. The limited communication range of the first basestation 410 allows the first base station 410 to only connect to thefirst sink 412 with wireless network. In the conventional method, asecond base station and a third base station are built when userequipment want to receive sensor data from a second sink 422 and a thirdsink 432. The method of present disclosure allows the first sink 412 totransmit a RTC to get second routing-information of the second wirelessnetwork 421 and third routing-information of the third wireless sensornetwork 431. The first sink 412 communicates with the second wirelesssensor network 421 according to the second routing-information. Thefirst sink 412 communicates with the third wireless sensor network 431according to the third routing-information. The first base station 410communicates with the third wireless sensor network 431 through thefirst wireless sensor network 411 and the second wireless sensor network421 as combination paths when the first base station 410 wants to getthe third sensor data of the third wireless sensor network 431. Thesecond wireless sensor network 421 comprises the second base station420. The second base station 420 connects to the second sink 422wirelessly (wireless devices not shown in FIG. 4). The second sink 422communicates with the first wireless sensor network 411 according to thefirst routing-information. The first base station 410 communicates withthe second base station 420 by combining the first wireless sensornetwork 411 and the second wireless sensor network 421.

FIG. 5 illustrates a flow chart of a method for the system of FIG. 1according to exemplary embodiment of the present disclosure. As shown inFIG. 5, a first sink transmits a RTC to first nodes in a first wirelesssensor network (S501). The first nodes relay data and instructionsaccording to first routing-information. The first nodes may be boundarynodes or non-boundary nodes (S502). The first nodes relay the RTC to thenext node when the first nodes are non-boundary nodes (S503). The firstnodes broadcast the RTC to the second wireless sensor network when thefirst nodes are boundary nodes (S504). The second nodes receive the RTCand determine whether or not to relay the RTC to the second sinkaccording to a flag of the RTC (S505). The second sink determineswhether or not to receive the RTC according to the flag (S506). Theprocess is terminated when the second sink does not receive the RTC(S510). The second sink transmits response to RTC to the first sink andexchanges the first routing information and the second routinginformation to the first sink (S507). The second sink determines thatthe response to RTC should be transmitted with security mode or withnon-security mode according to information of a packet. The informationof the packet includes a flag of security mode which can be set by user(S508). The second sink encryption can be by virtual private network(VPN) under the security mode (S509). The combining process isterminated after the second sink receives routing information from otherwireless sensor network (S510).

FIG. 6 illustrates in the flow chart an RTC, which is transmitted bysink according to exemplary embodiment of the present disclosure. Asshown in FIG. 6, a first sink transmits a RTC for discovering a secondwireless sensor network (S601). The first sink waits to receive aresponse to RTC and second routing information after a second sinkreceives the RTC (S602). The first sink transmits firstrouting-information to the second sink after receiving the response toRTC and the second routing-information. The first sink and the secondsink exchange the first routing-information and the secondrouting-information (S603). The first sink determines that the firstrouting-information to be transmitted in secure or non-secure modeaccording to information of the packet. The information of the packetincludes the flag of security mode, which can be set by user (S604). Thefirst sink encryption can be by VPN under the security mode (S605). Thecombining process is terminated after exchanging the firstrouting-information and the second routing-information (S606).

FIG. 7 illustrates in the flow chart a response to an RTC transmitted bysink according to exemplary embodiment of the present disclosure. Asshown in FIG. 7, a second sink receives a RTC from a first wirelesssensor network (S701). The second sink determines that the RTC bereceived or not received according to a flag of the RTC (S702). The RTCis ignored when the RTC is not to be accepted (S703). The second sinktransmits the response to RTC and second routing-information to a firstsink when the RTC is accepted (S704). The first sink and the second sinkexchange the first routing-information and the secondrouting-information (S705). The second sink determines that the responseto RTC and the second routing-information be transmitted in secure ornon-secure mode according to information of the packet. The informationof the packet includes the flag of security mode which can be set byuser (S706). The second sink encryption can be by VPN under the securitymode (S707). The combining process is terminated after exchanging thefirst routing-information and the second routing-information (S708).

FIG. 8 illustrates in the flow chart the RTC received by nodes accordingto an exemplary embodiment of the present disclosure. As shown in FIG.8, the nodes receive a RTC (S801). The nodes determine that the RTC istransmitted from own wireless sensor network or from other wirelesssensor networks according to a flag of the RTC (S802). The nodes may beboundary or non-boundary nodes (S803). The RTC is broadcasted when thenode is the boundary node (S804). The RTC is relayed to next node whenthe node is not the non-boundary node. In this way, the broadcasttransmittance of too many packets is avoided (S805). The nodes relay theRTC to their own sink when the RTC is transmitted from other wirelesssensor network (S806). The sink transmits the response to RTC afterreceiving the RTC. The nodes wait for receiving the response to RTC fromtheir own sink (S807). The second nodes relay the response to RTC tonext node after receiving the response (S808). The process of receivingthe RTC is then terminated (S809).

FIG. 9 illustrates a flow chart of the response to RTC (hereinafter“RTCresponse”) received by nodes according to exemplary embodiment ofthe present disclosure. As shown in FIG. 9, the RTCresponse is receivedby nodes (S901). The nodes determine whether the RTCresponse istransmitted from own wireless sensor network or from other wirelesssensor networks according to a flag of the RTCresponse (S902). TheRTCresponse is relayed to next node when the RTCresponse is transmittedfrom own wireless sensor network (S903). The RTCresponse is relayed toown sink when the RTCresponse is transmitted from other wireless sensornetwork (S904). The process of receiving the RTCresponse is thenterminated (S905).

Communication range of a wireless sensor network is limited by thelocation of data sink and sensing nodes. Sensor data cannot be obtainedthe communication range is exceeded. Therefore, a plurality of wirelesssensor networks can be utilized for covering the wider range ofapplication scenarios. The network packages cannot communicate with eachother in different wireless sensor networks. More nodes can be set forextending the transmission range of the wireless sensor network. By thisdisclosure, the communication range will be extended by exchanging therouting-information in different wireless sensor networks bytransmitting the RTC. The transmission of data by the wireless sensornetwork is not only improved, but the cost of the deployment of thewireless sensor networks is also reduced.

The exemplary embodiments shown and described above are only examples.Therefore, many details of such art are neither shown nor described.Even though numerous characteristics and advantages of the technologyhave been set forth in the foregoing description, together with detailsof the structure and function of the disclosure, the disclosure isillustrative only, and changes may be made in the detail, especially inmatters of shape, size, and arrangement of the parts within theprinciples of the disclosure, up to and including the full extentestablished by the broad general meaning of the terms used in theclaims. It will therefore be appreciated that the exemplary embodimentsdescribed above may be modified within the scope of the claims.

What is claimed is:
 1. A combination system of wireless sensor network,comprising: a first wireless sensor network, comprising: a first sinktransmitting request to combine and first routing-information; and;first nodes relaying data and instructions in the first wireless sensornetwork, the first nodes broadcasting the request to combine when thefirst nodes are boundary nodes, wherein the first routing-informationare established based on first transmission paths between the first sinkand the first nodes; a second wireless sensor network, comprising: asecond sink receiving the request to combine and obtaining the firstrouting-information from the first sink according to the request tocombine; and second nodes relaying the data and instructions in thesecond wireless sensor network, and wherein second routing-informationare established based on second transmission paths between the secondsink and the second nodes, wherein the second nodes receive request tocombine and determine whether the request to combine be relayed to thesecond sink according to a flag of the request to combine; and the firstsink and the second sink communicate with each other according to thefirst routing-information and the second routing-information.
 2. Thecombination system of wireless sensor network as claimed in claim 1,wherein the flag indicates types of instructions, the types of theinstructions comprise instructions from the same wireless sensornetwork, instructions from different wireless sensor networks and therequest to combine.
 3. The combination system of wireless sensor networkas claimed in claim 1, wherein the first sink and the second sinkexchange the first routing-information and the secondrouting-information through internet when the first sink and the secondsink are connected to the internet; and the first sink and the secondsink exchange the first routing-information and the secondrouting-information by the boundary node when the first sink and thesecond sink are not connected to the internet.
 4. The combination systemof wireless sensor network as claimed in claim 1, wherein the firstwireless sensor network further comprises a first base station connectedto the first sink by wireless communication, and wherein the first sinkcommunicates with the second nodes in the second wireless sensor networkaccording to the second routing-information.
 5. The combination systemof wireless sensor network as claimed in claim 4, wherein the secondwireless sensor network further comprises the second base stationconnected to the second sink by wireless communication, and wherein thesecond sink communicates with the first nodes in the first wirelesssensor network according to the first routing-information.
 6. Thecombination system of wireless sensor network as claimed in claim 1,wherein the first nodes broadcast the request to combine only when thefirst nodes are boundary nodes.
 7. A combination method of wirelesssensor network, comprising: obtaining first routing-information by firsttransmission paths between a first sink and first nodes; obtainingsecond routing-information by second transmission paths between a secondsink and second nodes; transmitting a request to combine by the firstsink; relaying data and instructions in a first wireless sensor networkby the first sink; broadcasting the request to combine by boundary nodesin the first wireless sensor network; receiving request to combine anddetermining whether the request to combine be relayed to the second sinkby the second nodes according to a flag of the request to combine;receiving the request to combine by the second sink and transmitting thesecond routing-information to the first sink; transmitting the firstrouting-information to the second sink by the first sink; andestablishing combination paths between the first sink and the secondsink according to the first routing-information and the secondrouting-information.
 8. The combination method of wireless sensornetwork as claimed in claim 7, wherein the flag indicates types ofinstructions, the types of instructions comprise instructions from thesame wireless sensor network, instructions from different wirelesssensor networks and the request to combine.
 9. The combination method ofwireless sensor network as claimed in claim 7, wherein the first sinkand the second sink exchange the first routing-information and thesecond routing-information through the internet when the first sink andthe second sink are connected to the internet; and the first sink andthe second sink exchange the first routing-information and the secondrouting-information by the boundary node when the first sink and thesecond sink are not connected to the internet.
 10. The combinationmethod of wireless sensor network as claimed in claim 7, wherein thefirst wireless sensor network further comprises a first base stationconnected to the first sink by wireless communication, and wherein thefirst sink communicates with the second nodes in the second wirelesssensor network according to the second routing-information.
 11. Thecombination method of wireless sensor network as claimed in claim 7,wherein the second wireless sensor network further comprises the secondbase station connected to the second sink by wireless communication, andwherein the second sink communicates with the first nodes in the firstwireless sensor network according to the first routing-information. 12.The combination method of wireless sensor network as claimed in claim 7,wherein broadcast the request to combine only by boundary nodes in thefirst wireless sensor network.